Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
26 Dec

Dear Mark: Salt and Blood Pressure

saltThe salt debate rages on outside these halls, but I’ve never really opened MDA’s doors to the tempest (beyond a short dalliance several years ago). Today, though, I am. We’ve likely all consumed a fair bit of sodium chloride over the past holiday weekend, and I imagine a few of us are wondering whether that’s a problem or not. Ever timely, reader John has written in with his salt story and a simple question: how much salt is suitable for humans?

Here’s his question:

I went Primal last year, and I’m down about 25 to 30 pounds and blood pressure is lowered. I have definitely followed your advice on low salt. For example, if I buy tomato sauce or paste, I get the “No Salt”, and I buy the low salt cashews, preferably with sea salt. What do you think about this new research that has come out, saying that salt is not that bad for you, and that it’s not actually related to heart disease? Just wanted your take.

John

There’s a lot of back and forth on salt, even among mainstream researchers. It used to be that dietary salt was absolutely evil, that it would spike your (everyone’s!) blood pressure and cause certain heart attacks and stroke. I mean, your average health-conscious grandparents probably still eat all their foods unsalted because, along with egg whites and 1% milk,  that’s just how you ate when you were trying to lower blood pressure and reduce the risk of an early death. But then stuff like the research to which John is most likely referring rolls around: this study (from the Cochrane Review in the American Journal of Hypertension) that Scientific American featured in its recent story, “It’s Time to End the War on Salt.” In fact, salt is kinda like the new egg. Will it or won’t it (kill you/clog your arteries/give you cancer/enter nefarious-sounding characteristic of necessary dietary component here)?

First of all, outright demonization of an element as important as sodium is silly and foolish. We literally have a physiological requirement for sodium (about 500 mg per day), and we come equipped with sensory apparati on our tongues (taste buds) specific to salt and extant for the express purpose of identifying salty things so we can consume them. It’s obvious that salt is necessary, and that it’s not poison. In fact, it:

  • Supports the nervous system – both sodium and chloride (also known as sodium chloride, or salt) are necessary for the firing of neurons.
  • Regulates blood pressure – keeps it from going too low or (usually) too high.
  • Helps maintain acid-base balance and blood volume.
  • Supports the function of the adrenal glands which produce dozens of vital hormones, including the stress and sex hormones.

But how much is too much? Is there such a thing as a limit to sodium intake?

Loren Cordain thinks the amount of salt average Americans get daily – almost 10 grams, or 3,875 mg of sodium – is excessive and evolutionarily discordant as indicated by the earliest evidence of salt mining by homo sapiens coming from China in 6000 BC and Spain in 6200 BC, well after the advent of agriculture. In his paper, he acknowledges the likelihood that coastal dwellers “may have dipped their food in seawater or used dried seawater salt,” but doesn’t find that the totality of evidence supports high sodium intake by humans during the Paleolithic. While I agree with 10 daily grams of refined salt being evolutionarily discordant and possibly excessive for some people, I think he’s overlooking something.

There’s plenty of evidence that the earliest humans were largely coastal dwellers with a fondness for seafood – particularly shellfish, which are rich in sodium. As I wrote in that shellfish post, basically any culture with coastal access left behind ample evidence of constant shellfish consumption. Some researchers are even suggesting that a bottleneck in human evolution occurred sometime between 190k and 130k years ago, when the total human population was reduced to about a thousand individuals living on the coasts of South Africa, eating a diet rich in seafood and especially shellfish. If it is from those thousand-odd humans that every current living human descends, and they were big shellfish eaters, I’d say it’s pretty likely that we can tolerate a decent amount of salt.

According to the USDA database, three ounces of raw clams, oysters, and mussels provide 510 mg, 90 mg, and 243 mg of sodium, respectively. I even think they’re undercounting the sodium content of oysters, personally. I regularly eat raw oysters on the half-shell, and there’s no way that mouthful of briny goodness contains just 90 mg of sodium. I’m guessing they measured the oysters rinsed and cleaned and from a jar, rather than slurped straight out of the shell. If our direct ancestors (all of them, assuming this bottleneck occurred) ate steady amounts of salty seafood straight out of the shell/sea, then salt can’t be bad, right?

Kinda. Some people are genuinely “salt-sensitive.” When they consume higher levels of salt, their blood pressure increases. When they drop the salt intake, their blood pressure drops with it. Studies indicate that of patients with hypertension, 51% are salt-sensitive (73% of African-American hypertensives are salt-sensitive), while 26% of normotensive patients are salt-sensitive. And since we know sodium chloride plays a physiological role in the regulation of blood pressure, this isn’t controversial in the least. But the majority of randomized controlled trials have been inconclusive regarding the effects of salt on hypertension, as the Cochrane Review mentioned, and some studies have found a slight increase in disease from “low-salt” diets. Another found “normal sodium” diets resulted in better outcomes for congestive heart failure patients than “low sodium” diets (less followup hospitalizations and certain blood markers). The evidence is mixed and murky, for sure.

That said, there’s way more to blood pressure than just salt intake. Like:

  • Fructose. Yes, fructose is strongly linked to hypertension. One study found that omitting one 12-oz sugary drink per day lowered BP. Dietary fructose increases salt absorption by the kidney, thus suggesting a synergistic effect between fructose and salt intake; you ditch the sugar and maybe the salt isn’t such an issue. Of course, salty and sweet often accompany each other in the industrial food world, probably to the kidney’s ultimate detriment.
  • Or potassium. Some research indicates that the dietary potassium:sodium ratio is more important than the absolute level of sodium in the diet. Although Ned Kock suggests that it may just be another marker for a healthy diet rich in real food.
  • Or general processed food intake. I’ve discussed this before, but consider that processed food accounts for most of the sodium in the average person’s diet. As one survey of the worldwide dietary sodium scene found, over 75% of sodium intake in North America and Europe comes from manufactured food. Asian countries consumed twice as much sodium on average than other regions, but consumed less processed food. I think it’s plausible that sodium intake is often just a proxy for processed food intake in epidemiology, and that’s partially explaining the rise in hypertension – not just the salt alone (although that obviously plays a role in certain individuals’ hypertension).
  • Or stress. Psychosocial stress is a likely cause of hypertension, even among people with low-salt diets. Well-adjusted, socially-fulfilled lab rats don’t get hypertensive on high-salt diets, while Malawi adults on low-salt diets get hypertensive when exposed to modern stressors.

The simple answer is that there is no one simple answer regarding the health effects of salt. It’s clear that while salt intake alone does not determine blood pressure for everyone, or even most, a certain portion of the population appears to be salt-sensitive; in this population, sodium intake increases blood pressure and decreasing intake decreases it. The genetics of salt-sensitive hypertension are complicated, undoubtedly with different epigenetic triggers and environmental contexts for the various manifestations, and experts are still mulling over specific recommendations in 2011.

I have a few somewhat specific recommendations, however:

Rather than obsess over the amount of salt in your diet, focus on eating enough potassium-rich foods, avoiding excessive fructose, and managing your stress. These will do more for your heart health, blood pressure, and overall enjoyment of life than measuring out 1/8 teaspoons of salt. You think calorie counting is bad? Try sodium ion counting!

Avocados, sweet potatoes, chard, and most fruits are excellent sources of potassium. Work those things into your diet, if they fit your template.

So’s meat, actually, particularly red meat. Just be sure to eat your meat closer to rare than not, as raw meat contains more potassium than cooked meat. And let your steak rest before slicing into it after cooking; the potassium’s (and flavor’s) all in the juice!

Don’t be scared of reasonable amounts of fruit, especially if you’re active; just avoid refined sweets and excessive amounts of excessively sweet fruit.

Pay attention to how you’re feeling. If I have lots of cured meats or salty cheeses or I eat out on the road several days in a row, I start feeling kinda… not great and somewhat bloated and heavy. On the other hand, sometimes I feel genuine cravings for salty food. In both cases, I listen to my body.

If you’re interested, run your meals through a Fitday or a Cronometer or something similar, and track your sodium, potassium, and fructose intakes.

Try to eat considerably more potassium than sodium, but through food (at least a 5:1 ratio). We like to point out how sodium might just be a proxy for processed food intake, but the same could be said for potassium intake, which might just be a proxy for real food intake. Consuming a refined diet with no vegetation or fresh meat but supplemented with potassium salts probably isn’t the same as consuming a real diet with actual food containing ample potassium (though potassium salts subbed for regular salt has been shown to reduce blood pressure in hypertensive patients with naked tails). And whether it’s the potassium or the lack of sodium or the real food providing the benefits, eating the real food and using real salt when applicable while avoiding processed and sweetened junk will get you there.

As for determining whether you need to reduce sodium intake, it’s pretty simple. If you have elevated blood pressure (and it’s not just white-coat syndrome) and you are salt-sensitive, reducing salt intake should lower blood pressure over the course of a few weeks. Cut your salt intake by around half to test for salt sensitivity. A quarter teaspoon in the meal instead of a half teaspoon, unsalted butter instead of salted butter – that sort of thing. Nothing super rigorous, just a general reduction in sodium. Increasing your potassium intake will “confound the results,” but this isn’t some stiff objective study on strangers you’re running; this is your life and your health, so don’t worry too much about eating that avocado cause it’ll throw off the effect of a reduction in salt intake.

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. Im not so sure I buy the idea that this article is selling. I hardly think the fact that salt is essential to our physiology is a very good argument that salt isnt bad for you. Cholesterol and fats are needed for your bodies normal functioning. Doesnt mean if i go around eating sticks of butter that Ill be fine and dandy. You can even drink too much water and itll be bad for you. The bottom line is that many people, through the intake of processed foods are consuming too much salt. And to say that ancient people had high salt diets is hardly a very convincing argument either. Just because these cultures could consume high quantities of salt and were still around as a result, does not mean a healthier lifestyle is one of reduced sodium intake. The article does however adress the differences in individuals in terms of salt sensitivity quite nicely. Certainly some individuals would benefit from a minimal sodium diet as others might benefit from small portion of natural sea salt. Overall, a diet of natural, raw food is whats best and most importantly one that is very well-balanced and diverse in its contents. Adding unnatural contents to these foods will only make them worse.

    stuart wrote on December 28th, 2011
  2. Lets get back to basics for a minute, i love salt, if i have a lot of bacon,ribs or anything else salty i get a raging thirst & i glug water like its going out of fashion. Now my personal view is this, if people drink too much water, one of the very dangerous side effects is hyponatremia (low blood sodium.)so does it also work the other way round??..now heres a simple scenario… ive taken in a heavy load of salt, my body knows this & signals me to drink a load of water & thats it, if i have too much salt i wont get stomach cancer, have a heart attack or stroke…i’ll just get thirsty!! ill just listen to my body……
    guys if im wrong i would appreciate someones input as i have no vast knowledge nor any qualifications on the subject concerned. thank you.

    chris wrote on December 28th, 2011
  3. Thank you for sharing this Mark. My Dad developed high blood pressure from excess renin being produced in a “ghost” or non functioning kidney. He absolutely eliminated sodium from his diet-he is hard core when he needs to be! And he was. Well, fast forward a few years later and his BP crept up. He has a new doctor at Duke who informed him he wasnt getting ENOUGH sodium and he needed it to balance his system out. He did so and BOOM, back to normal. Salt isn’t evil. Processed food is!

    Gina wrote on December 28th, 2011
  4. After reading the majority of this article , I am so glad to see that several posters addressed my questions about the salt source. I use himalayan pink salt in my finished products and have no issues.I feel I am using a “healthy”salt and am getting some needed minerals and trace elements. Wish this article had addressed the healthy salts and how they are good for you.

    Sherry England wrote on December 28th, 2011
  5. … we come equipped with sensory apparati on our tongues (taste buds) specific to salt and extant for the express purpose of identifying salty things so we can consume them.

    That logic is at least as sound for supporting the opposite theory, that those things are there so we can avoid things that are salty enough to taste, just as we often tend to avoid things that taste bitter. I know I have disliked salt for as long as I can remember, because of the taste and not for any health reasons.

    As I wrote in that shellfish post, basically any culture with coastal access left behind ample evidence of constant shellfish consumption.

    Wrong. For instance, archaeology shows that the Tasmanian aborigines (islanders, of course) gave up eating shellfish in remote prehistoric times, and they had a taboo against eating shellfish when they were discovered by Europeans. Also, for centuries Jews often had coastal access and also had a taboo against eating shellfish.

    P.M.Lawrence wrote on December 28th, 2011
  6. I am at work, so don’t have my references handy, but there was a controlled dietary study done(they provided all food and all meals to control levels). They did it in 2 stages. First stage was a 0 added salt for an extended period, and the second stage was the same diet but with very high added salt(exact same meal plan, from what I saw). The total different from several weeks at 0 salt to several weeks at very high salt was 1 point on the systolic and diastolic.

    Some people may be more susceptible than others, but… that just doesn’t seem to be significant to me.

    Also, I’ve seen a couple of things published recently that too low a salt intake is dangerous.

    james wrote on December 30th, 2011
  7. I agree that the dangers of salt is over hyped. However, I do find excess consumption of salt to lead to constipation and muscle cramping. I’m also starting to feel like it increases the chances of pulling a muscle. On the flip side I find if I don’t consume enough sodium, i experience the opposite of constipation.

    It’s only when I eat out do I need to be careful about excess salt consumption. It’s usually after a meal when I feel the need to down a gallon of water. That’s when I know I’m in a little trouble. :)

    Steve-O wrote on December 30th, 2011
  8. I’m very new to Primal Blueprint – in fact, I’m still reading the book – so I don’t have extensive experience with this lifestyle and salt intake.

    But, what I do know is this… For many years I ate mostly from scratch and didn’t add salt, however I would regularly get cravings for salty things like ‘Vegemite’ and potato crisps. In fact, the cravings were so bad I would eat vegemite off a spoon – and enjoy it!!!

    Fast forward a few years and I developed a stomach ulcer and then adrenal fatigue. It turns out I had hypochlorhydria.

    I now use Celtic salt – a lot. Turns out, I needed the Chloride as well as, if not more than, the Sodium.

    I learned the hard way that conventional wisdom is often unwise to follow!

    Aussie Girl wrote on December 30th, 2011
  9. Natural salt, whether brown (Real Salt) or gray (Celtic) or pink (Himilayan) is the way to go, avoid bleached white salts especially those with additives such as anti-caking agents. A diet of fresh whole foods should supply the potassium, magnesium and other minerals you need to balance the sodiun.
    For those of you looking for more iodine, sea food, or sea weed aka sea vegetables are good sources, Try Dulse flakes sprinkeled on top of salads, veggies, eggs, soups or stews for an iodine boost.

    Reader wrote on December 31st, 2011
  10. I noticed you didn’t mention anything about diabetes and salt intact in your article. Is there any danger being diabetic with high blood pressure and to much salt or potassium?

    Joe A. wrote on January 10th, 2012
    • Sorry I meant salt intake not salt “intact.”

      Joe A. wrote on January 10th, 2012
    • If you’re talking T2, we usually have high insulin levels to overcome insulin resistance. Insulin causes potassium loss as one of it’s physiological functions.

      On top of that, the most common way to control bG is limiting carb intake, and low-carb causes potassium loss.

      I had elevated bp for years and ever-increasing doses of beta blockers and ace inhibitors made no difference. However, my bp went down to high-normal when I started on raw milk and then down to medium-normal when I started supplementing potassium. I did pretty heavy-duty supplementing, as K-dur, for quite some time before I managed to mostly stabilize.

      I have a tendency to edema in my feet and can predict my bp based on the size of my feet. I can also control both edema and bp by using my foot size to determine when I need to take a K-dur.

      Mg also helps prevent K loss. I use both a homemade “magnesium oil” (saturated MgCl2 solution in a spray bottle) and epsom salts in bath. Diabetics also tend to be low on Mg, so it’s a win-win.

      jpatti wrote on August 25th, 2013
  11. Hi Mark

    If they eat shellfish and it demonstrates salt is not bad for us, then this is valid too to affirm that high-carbs plants aren’t either?: “That area has a super high diversity of below-ground tuberous plants, which have high carb loads. People are excellent foragers for them. You need a digging stick and there wouldn’t be a lot of animal competitors,” he said. “And the tuberous plants are adapted to arid environments.”

    i’m confused by that.

    Sorry for my english.
    Franco.

    Franco wrote on June 13th, 2012
  12. I think potassium is a rather overlooked salt. When you start a low carb diet what usually occurs is a loss of water, which not only includes a loss of sodium but a loss of potassium too. With heavy exercise, you also lose potassium through sweat.
    Low potassium can cause weakness, muscle cramping, fatigue and breathlessness (sounds a bit like low carbohydrate flu).
    I’d say if you don’t have high blood pressure or are being treated for fluid retention, taking potassium salts or tablets seems like a good idea, there aren’t very high levels of potassium in food, not enough to make up for depletion anyway.

    Heather wrote on July 11th, 2012
  13. It’s been my experience that not having enough potassium in the diet leads to problems, not having too much salt.

    If you have too little potassium, than any amount of salt is going to be problematic.

    Loren wrote on April 2nd, 2013
  14. One spring on an unusually early hot and humid day I had done a lot of splitting wood and was really dragging by 11 AM. I went in the house and poured a glass of my favorite drink at the time, orange juice. After a while I realized I was just sipping it. I thought “wow, I’m supposed to be thirsty and I’m just sipping this?” A light bulb went on, I ate three pinches of salt, and in less than a minute I felt like Superman.

    The lesson is: when you are low in salt you are not thirsty and you may be craving salt or salty snacks. When salt is high and potassium low you want fruit or fruit juice rather than plain water. (You might drink plain water while wanting fruit juice more.) Plain water is only satisfying when salt and potassium are balanced or when you are pretty well dehydrated.

    This is a great site and blog, maybe the best I’ve ever seen in its field. Need to read a lot more…

    Ed Hamerstrom wrote on July 5th, 2013
  15. I’m having half a teaspoon in water every morning when I wake. Is this too much? I also add some to each meal.

    Terry wrote on November 30th, 2013
  16. Regardless of all studies made and published, reducing salt (amongst other action) in my diet was what did it for me. I had a high blood pressure and my doctor suggested me to take action. My blood pressure was pretty high, in the 160/100 mmHg range (highest ever measured was 164/102 mmHg). That’s pretty high, considering I’m only 29 years old (blood pressure rises naturally over years and especially after the age of 40). So, when I started exercising (I lowered my fat percentage) and reduced my salt intake, my blood pressure dropped to a much lower level and is now at about 135/85 mmHg. This is still considered an increased blood pressure (see this blood pressure chart http://healthiack.com/health/blood-pressure-a-health-indicator#blood-pressure-chart), but I’m working towards the “ideal” 120/80 mmHg. Maybe I can never reach that mark again, but I will do my best.
    I used a lot of salt in my diet. I put salt on everything, fries, pizza, potato, salad… I reduced the intake of salt for at least 75%. I still use salt (because body needs salt), but I use it with moderation.
    So if you’re in doubt whether reducing salt intake lowers blood pressure or not – give a “less salt diet” a try. It might work for you too. But remember, sometimes an increased blood pressure may indicate other medical condition (and not just poor diet and physical condition) so make sure you consult with your doctor first.

    Regards,
    Gary

    gary wrote on January 6th, 2014

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